High-voltage electron tube



June 9, 1925.

' I w. DAUMANN HIGH VOLTAGE ELECTRON TUBE- Filed F'eb."7, 1922 Patented June 9, 1925.

UNITED STATES PATENTOFFlCE.

winnnnm DAUMANN, ornniunune, GERMANY, AssIeNon. To 0. n. r. minnnn, nonrennnonnnnrnnmx, or HAMBURG, GERMANY, A CORPORATION or enn- ELECTRON TUBE.

' Application filed February 7, 1922 Serial no. 534,695.

To all whom it may concern:

Be it known that I, WILHELM DAUMANN, a citizen of Germany, and residing at Hamburg, Germany, have invented certain new and useful Improvements in High-Voltage Electron Tubes, of which the following is a specification.

My invention relates to improvements in high voltage electron tubes, such as valve tubes, Riintgen tubes, and the like. As is known in the art, in tubes of this 'class the incandescent wire from which the electrons are emitted is subject to high mechanical strain by reason of the electric field of forces, so that the said wire is frequently broken. For this reason it has been proposed to shield the wire by protective wires disposed in front thereof, or to dispose the electrodes a large distance apart. This however is objectionable, because'the removing of the gas from the metallic parts of the tube and the operation of the tube are interfered with, and in case of valve tubes the inner resistance is increased in an objectionable degree.

The object of my improvement is to provide a tube in which the incandescent wire or a system of wires is not liable to be torn which the said objectionable features are avoided. With this object in view my invention consists in constructing the incandescent wire or system of such wires in the form of a loop or loops having their convex parts facing the anode and disposing the said loop near the anode. The radius of curvature of the arc-shaped incandescent wire corresponds to the power of the attraction acting on the wire, for which reason the parts which are next to the anode and which therefore are subject to the highest strain have a sharp curvature, while the parts which are near the joints connecting the wire to the terminals have slight curvatures or are straight, in view of the small attraction. I In order that the invention be more clearly understood several examples embodying the same have been shown in the accompanying drawing, in which Fig. 1 is a longitudinal section showing a valve tube provided with an incandescent wire in the form of a single loop.

Fig. 2 is a similar section showing a valve .tube in which the incandescent wire is in the form of two loops, and

Fig. 3.,is a similar section showing a Riintgen tube provided with an incandescent cathode.

In the example shown in Fig. .1, the incandescent wire 1 is in the form of a hair pin which is spread apart at its ends 3' jointed to the terminals 7 and which faces with its looped part the anode 2. The looped incandescent wireis disposed coaxially of and a slight distance away from the anode 2. Therefore the electrostatic forces acting on the incandescent wire fall oif from the vertex of the wire to the joints '3 thereof. Thereby the mechanical strain on the incandescent wire is materially reduced, so that the wire is not broken even in case of high voltage.

In Fig. 2 I have shown a valve tube in which the incandescent wire is in the form of a system composed of two looped wires 1 and disposed longitudinally of a tubular anode 2. The form of the individual loops of the system corresponds to the loop shown in Fig. 1. In this construction an incandescent wire of greater length can be provided, whereby a. more powerful emission of electrons is obtained, which is particularly important in case of valve tubes.

In the example shown in Fig. 3 in lieu of the anode 2 an anticathode 5 is provided, which is made from a metal of high melting point and high atomic weight, such for example as tungsten, tantalum, and the like. The anticathode is mounted on wires 4 and it. is disposed a small distance away from and coaxially of the incandescent cathode 6 made in the form of a hair pin. The space remaining between the flat face of the anode or anticathode' (2, 2, or 5) and the adjacent portion or apex of the cathode (1, 1', or6) is considerable relatively to the distance between. said face and a point halfway between said apex and the attached ends (3 in Fig. 1) of the cathodefilaments. This distance may be termed the median distance between the cathode filament and the opposed flat face of the antica-thode. In the examples illustrated, the ratio of said space to said distance is about as 2 to 3, and in any event, the distance between the face of the anticathode and the apex of the filament should be at least about one-half of the median distance defined above. If the a ex of the filament is too near the anticatho e, the filament Will break down when high voltages are used.

It will be understood that in same cases in the tube described with reference to Fig. 3 an incandescent Wire electrode formed into a plurality of loops is provided.

It will be noted that in every instance the incandescent wire is given a special form for the purpose of enabling it to stand the high mechanical strain due to the action of the electric field.

I claim:

A high voltage electron tube, comprising a receptacle, an anticathode element'located' in said receptacle and having a flat face in the central portion of the receptacle and at a right angle to the longitudinal axis of the receptacle, and a. filamentary cathode element likewiselocated in said receptacle and extending substantially lengthwise thereof, said cathode being bent sharply at its end or apex which faces the anticathode, such apex being located at the central portion of the receptacle and the space between such apex and the opposing face of the anticathode beingunobstructed, and the distance between the flat face of the anticathode and the apex of the cathode element being at least about one-half of the median distance between said cathode element and the flat face of the anticathode.

In testimony whereof I hereunto aflix my signature in the presence of two witnesses.

WILHELM DAUMANN.

Witnesses:

HERMAN LijBBE, CARL REINSGHILDT. 

